DE2952519A1 - METHOD FOR PRODUCING ACETYLENE FROM COAL - Google Patents

Description

Process for the production of acetylene from coal

Acetylene is formed from other hydrocarbons at temperatures above approx. 1,400 ° C. Since it is unstable, without countermeasures it would after a short time decompose to the equilibrium concentration, which is very low at 1,400 ° C and becomes even lower at lower temperatures. Therefore, at the moment when the acetylene concentration is highest, one must suddenly lower (quench) the temperature in order to freeze this state of high acetylene concentration. This sudden drop in temperature can occur through the injection of water, gaseous, liquid or solid hydrocarbons, through recirculated products or in some other way.

An arc discharge can be used to generate the high temperatures necessary for acetylene formation. Direct and alternating current (three-phase current) are equally suitable. The ratio of current to voltage depends on the arc length and the arc gas and is determined by the reactor geometry and the mode of operation - e.g. B. with or without gas recirculation - fixed. Both methods with a current / voltage ratio greater than one and those with a current / voltage ratio less than one are suitable for generating acetylene. For example, a gas vortex can be used to stabilize the arc (Proc. 8th World Petroleum Congress (1971) Volume 4, pages 379-388) or a

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Magnetic field that sets the arc in rotation (US Pat. No. 3,073,769).

The reaction process in the arc reactor is different for all raw materials. However, the following applies to all raw materials that the formation of acetylene competes with its decomposition, so that a maximum of the concentrations in the course of the reaction of acetylene and the radicals that form acetylene when quenched. For optimal acetylene production it is necessary, regardless of the raw material, that this maximum is reached at the point in the reactor the products are quenched.

To achieve suitable conditions, the gas is blown through the arc with an energy between 5 and 20 kJ / 1 (in the normal state) heated and so much coal is metered into the reactor that the ratio of electrical power to coal flow 4,000 to 40,000 kJ per kg of coal. It is advantageous if the gas that is fed into the reactor has a high Contains hydrogen content. A major reason for this is that hydrogen inhibits the decomposition of acetylene.

It is known to produce acetylene from gaseous or liquid hydrocarbons, for example from methane to crude oil (Ullmanns Enzyklopadie der technischen Chemie, 4th edition (1974) Volume 7, pages 47-49).

It is also known, also from bituminous coals with a content of volatile components (i.waf) over about 38 wt .-% to produce acetylene in the arc reactor, but the

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Acetylene yield was only 7-9% by weight (P. H. Given, Report to Office of Coal Research, U.S. State Department of Interior, Report No. 61, Interim Report No. 5, pages 4 and 5).

The economics of a method of making Acetylene from coal depends essentially on the acetylene yield, the acetylene concentration in the product gas and the specific Energy requirement (energy requirement for the production of 1 kg of acetylene): the acetylene yield and concentration must be as high as possible high and the specific energy requirement as low as possible.

The invention is based on the object of using coal in an electric arc reactor To produce acetylene in the highest possible yield with the lowest possible specific energy requirement.

This object is achieved according to the invention in that 9 Smaller than 0.5 mm finely ground coal with a volatile matter content (i.waf) between 25 and 44%, preferably between 30 and 40%, and an organic oxygen content (i.waf) below 9% in 2 to 4 grain fractions separately and each of these grain fractions to a special arc reactor is abandoned, with the coal after a dwell time in the hot gas, which is roughly inversely proportional to the 3rd root of the specific outer surface of each Coal fractions is long, is quenched.

The invention is based on the knowledge that the acetylene yield becomes higher as the pyrolysis of the coal is completed more quickly; because with a fast pyrolysis the end of the Pyrolysis will break down less of the acetylene initially formed

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than with a slow one. According to the method according to the invention the pyrolysis process can be shortened by two different measures; either one uses a coal, the middle one Grain diameters very small or their specific external

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re surface is very large, namely up to 1.54 m / cm, measured according to the Blaine method, or you take care of it - also with coarser grain sizes - that the breadth of the grain size distribution of the coal is as small as possible, for example the uniformity parameter should η of a Rosin-Rammler-Sperling-Bennet distribution (RRSB distribution) (Ullmanns Encyklopädie der Technische Chemistry, 4th Edition, Volume 2, page 27) 1.2 - 2.5.

According to the invention, the specific outer surface should therefore

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of the coal between 0.5 and 2.0 m / cm. She will for example determined by the Blaine method (DIN 66 127. ASTM (204-68).

In addition, according to the invention, the grain size distribution should each Coal fraction is the mean slope of the grain size curve in the Rosin-Rammler-Sperling-Bennet network between the passes of 10% and 80% are at least 1.2.

As a starting material for the production of acetylene, basically all coals from brown coals over the various are suitable high-ranked bituminous coals to anthracites. The acetylene yield, however, depends on the degree of coalification of the coal. According to the invention, the content of the coal is organic Oxygen is just as important for an assessment as the volatile content. The oxygen content of the coals connects in the arc reactor with part of the fugitive

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term carbon to carbon monoxide, so that this carbon is not available for acetylene formation. In the case of lignite, which has a higher proportion of organically bound oxygen, the acetylene yield is lower for this reason than in the case of highly volatile hard coals, although they have a higher content of volatile components.

The process according to the invention is particularly advantageous if a ground coal, which generally has a broad grain size distribution, is broken down into several grain fractions with narrower grain size distributions by suitable measures, such as air sifting, and each of these grain fractions is in a separate arc reactor, in which the residence time of the coal in the hot reaction zone is adapted to the grain size, is converted to acetylene.

Embodiment

Hard coal with a grain size of less than 0.5 mm with a volatile matter content (i.waf) of 38.6% by weight and an organic oxygen content (i.waf) of 8.2% by weight is divided into three different Konrlargevertei lungs a reactor for the production of acetylene from coal abandoned, in which a gas mixture of hydrogen and argon by an arc it is heated, which burns between a rod-shaped cathode and an anode designed as a hollow cylinder. The anode will

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cooled by water. The arc is set in rotation by a magnetic coil. The power of the arc, reduced by the power loss dissipated by the cooling water, is 19.7 kW. Into the hot hydrogen / argon mixture coal is injected with a stream of hydrogen at 84 g / min. The total gas stream introduced into the reactor is 156 1 / min, consisting of 91 vol .-% hydrogen and vol .-% argon. In the reactor room, the coal turns into acetylene implemented. The reaction products are quenched with a hydrogen cooled down.

1. The grain size distribution of the starting coal is characterized by 90% by weight smaller than 65 μm, 50% by weight smaller than 13 μχα and a uniformity parameter η of the RRSB distribution of 0.8 (curve 1 in Figure 1). The Blaine surface is 1.26 m / cm. The residence time of the carbon in the reaction space until the quench is 2.8 10 s.

An acetylene yield of 0.30 kg of acetylene per kg of coal is obtained. A specific energy requirement is calculated from this (without the energy loss in the cooling water) of 13.0 kWh / kg acetylene.

2. The starting coal of Example 1 is broken down into a fine and a coarse grain fraction by air separation, whereby The fine grain fraction accounts for 39.7% by weight of the starting coal used. 90% by weight of the fine grain fraction are less than 9 ^ in and 50 wt .-% less than 4.8 / in, the Uniformity parameter η of the RRSB distribution is 2.0

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(Curve 2 in Fig. 1), the Blaine surface of the fine-grain

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fraction is 2.30 m / cm. The residence time for the fine grain fraction in the reaction chamber is 2.3 10 s. This residence time is derived from the residence time of the grain distribution used in Example 1 and the ratio of the Blaine surface of the starting coal to the fine grain fraction according to the formula residence time of the fine grain fraction = 2.8 χ - ^ Vl, 26 / 2.30 'ms calculated. For the fine-grain fraction, an acetylene yield of 0.41 kg of acetylene per kg of coal is obtained. This results in a specific energy requirement (excluding the energy lost in the cooling water) of 9.5 kWh / kg acetylene. The higher acetylene yield and the lower specific energy requirement compared to Example 1 are explained by the higher Blaine surface and the narrower grain distribution, which is expressed in the larger uniformity parameter η of the RRSB distribution.

3. The coarse grain fraction resulting from the air classification accounts for 60.3% by weight of the starting coal used. 90% by weight of the coarse-grain fraction is smaller than 50 μm and 50% by weight is smaller than 22 μm, the uniformity of the RRSB distribution is 1.4 (curve 3 in Fig. 1), the Blaine -Surface is 0.47 m / cm. The residence time for the coarse grain fraction in the reaction chamber is 3.9 χ 10 s; This residence time is calculated from the residence time distribution of the grain used in Example 1 and the ratio of the Blaine surface areas of the starting coal to the coarse grain fraction according to the formula residence time of the

Coarse grain fraction = 2.8 χ - ^ vI , 26 / 0.47 'ms calculated. He holds for the coarse fraction an acetylene yield of

- 10 -

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0.28 kg of acetylene per kg of coal. A specific energy requirement is calculated from this (without the amount of loss in the cooling water) of 14.0 kWh / kg acetylene. The acetylene yield, which is lower than in Examples 1 and 2, and the higher one specific energy requirements are explained by the smaller Blaine surface. The effect was compared by that for example 1 narrower grain distribution, which is reflected in the larger uniformity parameter η of the RRSB distribution expresses not balanced.

If the acetylene yield and the specific energy requirement for the total of both grain fractions are calculated from Examples 2 and 3, taking into account the respective proportions, an acetylene yield of 0.33 kg acetylene per kg coal and a specific energy requirement of 11.8 kWh / kg are obtained Acetylene. Compared with the yield and the specific energy requirement of the non-fractionated coal in Example 1, this result means an advantage which is achieved through the narrower distributions (larger η values) of the fine and coarse fractions.

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Claims (3)

BERGWERKSVERBAND GMBH EXPERIMENTAL COMPANIES OF MINING RESEARCH 4300 Essen 13 (Kray), December 21, 1979 Froiu-Fijdier-Weg 01 T.l.fon (0201) 105-1 Procedure for Manufacture of acetylene from coal Claims Process for the production of acetylene by direct conversion of lignite or hard coal into a hydrogen-containing gas, which is heated by an electric arc with an energy of 5 to 20 KJ / 1 (in the normal state) and with. so much coal is loaded that the ratio of electrical power to coal flow is 4,000 to 40,000 KJ / kg coal , the product gas being quenched with cold gas, cold liquid hydrocarbons or water, characterized in that to less than 0.5 mm Finely ground coal with a volatile content (i.waf) between 25 and 44 %, preferably between 30 and 40%, and an organic oxygen content (i.waf) below 9 % separated into 2 to 4 grain fractions and each of these grain fractions a special arc reactor is given, the coal is quenched after a residence time in the hot gas, which is approximately inversely proportional to the 3rd root of the specific outer surface of the individual coal fractions. 13ÖÖ27 / O683 ORIGINAL INSPECTED 2. The method according to claim 1, characterized in that the specific outer surface of the finely ground coal to less than 0.5mm (determined by the Blaine method) 2 3 is between 0.5 and 2.0 m / cm. 3. The method according to claim 1 and 2, characterized in that in the grain size distribution of each coal fraction, the mean slope of the grain characteristics in the Rosin-Rammler-Sperling-Bennet network between the passes of 10% and 80% between 1.2 and 2.5 amounts to. 130027/0683